Combination thermostatic switch and plug connecter



Nam 4 193(1 P. A. PETERSON COMBINATION THERMOSTATIC SWITCH AND PLUG CONNECTER Filed April 25, 1928 wen??? j? d. I Zeferaom Patented Nov. 4, 1930 PATENT OFFICE PETER A. PETERSON OF CHICAGO, ILLINOIS COMBINATION THEBMQSTATIC SWITCH AND PLUG CQNNECTER Application siea am; as,

My invention relates, generally to heat-- controlling devices for electric irons, hot plates, electric percolators, and similar electrically-heated devices,

It is an object of my invention to provide improved means for controlling electric circuit to an electrically-heated device.

A further objec" is to provide device of this kind vhich forms a, part of the connecting socket may readily be used with any heating appliance.

A further object is to provide device of this kind in which the temp ature which the devic readily be adjus A further proved device of this type which will save electric current and prevent fires and accidents due to overheating or the electric appliance to which it is attached.

A further object is to provide an improved thermally-controlled switch which is simple in construction, may be economically manufactured and which is efiicient in operation.

Other objects will appear from the tollowing description, ref rence being had to the accompanying drawings, in which Fig. l is an elevation of an electric iron with my improved combination connecting socket and thermostatic switch applied thereto;

Fig. 2 is a side elevation of my improved thermostatic switch and connecting socket;

Fig. 3 is a longitudinal sectional view thereof taken on the line 3-3 of Fig. 2; and

Fig. l is a sectional view taken on the line 4-4 of Fig. 3.

In the past, electric irons and similar appliances have been equipped with thermostatically-controlled switches but these switches have always been incorporated as a part of the iron itself and are therefore relatively inaccessible for repair or replacement. T have therefore provided a novel form of thermostatic control switch which is incorporated as part of the socket used to make the electrical connection to the iron.

In Fig. 1, T have shown the conventional 1928. Serial No. 272,616.

electric iron 6 as having a pair of connecting prongs 8 over which a plug socket connecter 10 is fitted. The connecter comprises a pair of body portions 12 and 14 which are secured together by bolts 16 and 18 which pass through the body portions whose heads and nuts tit in sui able recesses 20 formed in the body portions 12 and A.

An electric current is conducted to th connecter 10 through a pair of conductors if 22 which are protected by coil spring 2%; the end of the latter heiheld in suitable groove 26 "formed the portions 12 ano 14. The ends of the conductors are secured to the portion 12 by screws 28 and 30 which are threaded in srdtable nuts 32. These nuts are preferably firmly imbedded in the portion 12. The screw 30 holds the end or one of the conductors in electrical contact with a connecting bar 34:, the'other end of which is eyelet riveted to a pair of resilient members 36 which together form a suitable spring socket for the reception of one of the prongs 8.

similar socket for the other prong 8 is provided by a pair of resilient members 38. These members are secured with a bimetallic thermostatic element 40 to the body portion 12 by a screw 42 which is threaded in a nut 44, the latter being imbedded in the body portion 12. The other end of the thermostatic element 40 carries a suitable tungsten or platinum contact point t6 which is adapted to make an electric connection with a similar contact point 48 secured to the end of a screw 00 which is threaded in a support 52. The end of the screw has a knob 54 of insulating material and has a pointer 56 attached thereto. This pointer cooperates with an indicating dial 58 formed upon the surface of the body portion 14.

The body portion 1% has a suitable aperture 60 to receive a portion of the support 52 and to permit the screw 50 to be threaded into the support. A stop pin 62 is set in the body portion 14 and adapted to be engaged by the pointer 56 and thus limit rotative movement of the screw 50. The support 52 is held in place by the screw 28 and is, of course, of conducting material so as to transmit the electrical current from one of the conductors 22 to the contact point 48.

The thermostatic element 40 may be made of any two suitable metals having sufliciently different coeflicients of expansion.

In operation, the connecter is pushed over the prongs 8 in the usual manner and the current is. thus supplied to the iron through one of the conductors 22, support 52, contact points 48 and 46, thermostatic element 40, and

socket members 38. The return circuit is throughthe socket members 36, bar 34 and the other conductor 22. As the iron heats up to a predetermined temperature, the thermostatic element will be heated through conduction of heat through the prong8 and socket member 38. The electrical resistance of the thermostatic element 40 is insuflicient appreciably to afiect its temperature when the connecter is used with the usual appliances drawing a relatively low amperage current.

As the element 40 becomes heated it bends away from the position shown in full lines in Fig. 3 to the position shown in dotted lines in said figure, thereby breaking the electrical circuit to the iron. As the temperature of the iron again drops, the temperature of the element 40 will be correspondingly lowered and at a predetermined temperature will again bend back to the position shown in full lines in Fig. 3 and close the circuit to the iron.

The temperature at which the electrical cir cuit is opened and closed may be Varied by adjusting the screw 50. By turning the screw clockwise (Fig. 2) the contact point 48 will be moved to the left (Fig. 3) and thus it will require a higher temperature to cause the element 40 to bend sufficiently to open the circuit.

When the screw is turned counterclockwise to the position where its pointer-abuts against the stop 62, the contact points 46 and 48 will be separated, thereby interrupting the circuit to the iron irrespective of the temperature of the latter.

When it is desired to use the connecter with an appliance which requires an unusually high voltage and amperage current, a suitable quick snap-over mechanism may be illcorporated in the device to cause sudden separation of the contact points. However, in normal use, such mechanism is unnecessary.

The invention is capable of wide variation within equivalent limits and I contemplate such variation as may be desirable or usefulin the particular adaptation bf the invention shown, or in its adaptation to other devices. I do notrestrict myself in any unessential particulars, but what I claim and desire to secure by Letters Patent is O x 1. In an electric plug socket connecter for electric heating appliances, the combination of a pair of insulating body members secured together, a pair of sockets adapted to receive the connection prongs of a heating appliance and transmit electric current thereto and heat therefrom, each of said sockets being formed in two halves, a bimetallic thermostatic element having one end positioned between the ends of the halves of one of said sockets and extending longitudinally of said body members, a screw for fastening said socket halves and said element to one of said members, a substantially Z-shaped support secured to said last-named member and having a .portion overlying the free end of said thermostatic element, and a screw threaded in said portion of said support and having a point for contact with the free end of said thermostatic element, said screw extending through an screw threaded in said portion of said support extending outwardly through said aperture and having a manually engageable insulating head thereon, and non-fusible contact points, one secured to the free end of said thermostatic element and the other to the 0nd of said screw. 4

In witness whereof, I hereunto subscribe I my name this 21st day of April, 1928.

PETER A. PETERSON.

the position of the contact and having a por- 

